title: Differences in the metabolomic signatures of porcine follicular fluid collected from environments associated with good and poor oocyte quality.
abstract: The microenvironment of the developing follicle is critical to the acquisition of oocyte developmental competence, which is influenced by several factors including follicle size and season. The aim of this study was to characterise the metabolomic signatures of porcine follicular fluid (FF) collected from good and poor follicular environments, using high-resolution proton nuclear magnetic resonance (1H-NMR) spectroscopy. Sow ovaries were collected at slaughter, 4 days after weaning, in summer and winter. The contents of small (3-4  mm) and large (5-8  mm) diameter follicles were aspirated and pooled separately for each ovary pair. Groups classified as summer-small (n=8), summer-large (n=15), winter-small (n=9) and winter-large (n=15) were analysed by 1H-NMR spectroscopy. The concentrations of 11 metabolites differed due to follicle size alone (P<0.05), including glucose, lactate, hypoxanthine and five amino acids. The concentrations of all these metabolites, except for glucose, were lower in large FF compared with small FF. Significant interaction effects of follicle size and season were found for the concentrations of glutamate, glycine, N-acetyl groups and uridine. Succinate was the only metabolite that differed in concentration due to season alone (P<0.05). The FF levels of progesterone, androstenedione and oestradiol were correlated with the concentrations of most of the metabolites examined. The results indicate that there is a distinct shift in follicular glucose metabolism as follicles increase in diameter and suggest that follicular cells may be more vulnerable to oxidative stress during the summer months. Our findings demonstrate the power of 1H-NMR spectroscopy to expand our understanding of the dynamic and complex microenvironment of the developing follicle.
authors.affiliation: INRA, UMR85 Physiologie de la Reproduction et des Comportements, Équipe Interactions Cellulaires et Fertilité, 37380 Nouzilly, France.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bertoldo
authors.forename: Lydie
authors.initials: L
authors.lastname: Nadal-Desbarats
authors.forename: Nadine
authors.initials: N
authors.lastname: Gérard
authors.forename: Alexis
authors.initials: A
authors.lastname: Dubois
authors.forename: Patricia K
authors.initials: PK
authors.lastname: Holyoake
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Grupen
mesh_terms: D000818:Animals; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D055442:Metabolome; D015999:Multivariate Analysis; D009865:Oocytes / Q000502:physiology*; D012621:Seasons; D013256:Steroids / Q000378:metabolism; D013552:Swine
chemical_list: D013256:Steroids